Answers

Compiling Okular

Building CXX object okular/generators/poppler/CMakeFiles/okularGenerator_poppler.dir/generator_pdf.o
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp: In member function 'Okular::TextPage* PDFGenerator::abstractTextPage(const QList<Poppler::TextBox*>&, double, double, int)';:
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1088: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1091: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1098: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1101: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1113: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1115: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1122: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1125: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1134: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1136: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1144: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1147: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1158: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1160: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1167: error: 'class Poppler::TextBox'; has no member named 'edge';
[...]/kdegraphics/okular/generators/poppler/generator_pdf.cpp:1170: error: 'class Poppler::TextBox'; has no member named 'edge';
make[2]: *** [okular/generators/poppler/CMakeFiles/okularGenerator_poppler.dir/generator_pdf.cpp.o] Error 1
make[1]: *** [okular/generators/poppler/CMakeFiles/okularGenerator_poppler.dir/all] Error 2
make: *** [all] Error 2

If so, most probably you updated from Poppler 0.6.x or previous to Poppler 0.8.What you can do is simple:

rm CMakeCache.txt

in the build directory of Okular. Then run cmake again, and all should work as expected.

General usage

By default, Okular saves annotations in the local data directory
for each user. Since KDE 4.9, it's optionally possible to store them directly in
a PDF file by choosing "File -> Save As...", so they can be seen in other
PDF viewers.Note that this feature requires Poppler 0.20 or newer for regular PDF
documents. If the PDF document you are annotating is encrypted, this feature
requires Poppler 0.22 or newer.

Since KDE 4.2, Okular has the "document archiving" feature. This is
an Okular-specific format for carrying the document plus various metadata
related to it (currently only annotations).You can save a "document archive" from the open document by choosing "File
-> Export As -> Document Archive".To open an Okular document archive, just open it with Okular as it would be eg
a PDF document.

If you're annotating a PDF document, you can also save annotations
directly in the PDF file (see previous question)